The time resolution process of excitation intensity of spectral lines in the spark light source is measured. In the spark, operating under the critical damping state, with flash time at about 2×10-6 Sec., the ion lines of higher excitation potential first appear and appear shortly. Experiments show that, as to time, two lines, All and MoⅡ, piled up at 3961.5?, may be fully seperated, providing the possibility to avoid the interferences and to use the sensitive line as spectrum analysis.